The present invention relates to a photometer of the variety wherein modulated infrared radiation passes through a container, vessel, cuvette or the like and the exiting radiation is duly detected and the detection result is processed.
A variety of photometers are known and they serve primarily for purposes of quantitatively ascertaining the particular proportion of a particular gas within a host or carrier gas. Photometers using infrared radiation are constructed in order to operate under the principle of dispersion but other varieties are known which do not function or operate in the dispersive mode. Generally speaking reliable and troublefree operation is guaranteed if in addition to the measured value continuously a reference value or signal is provided or derived and these quantities are then brought into relation to each other.
A typical example is the infrared gas analizer URAS 2 T traded under this designation by the assignee corporation and described in a flier 20-1.12 of Hartmann & Braun AG published May 1983. This analyzer uses infrared radiation emanating from a source wherein the radiation is modulated by means of a diaphragm wheel. The modulated radiation is passed through a biparted cuvette or measuring chamber to be received by the chambers of a biparted detector. Such a device is operable under utilization of an intermittent operation of the radiation source which intermittency is the equivalent of the modulation; a diaphragm wheel is not needed in this case.